1. Field of the Invention
This invention relates generally to the field of fluid line couplings and in particular to locking assemblies for utilization in fluid line couplings which use push-on fittings. Still more particularly, the present invention relates to locking assemblies which may be simply and easily applied to such fluid line couplings.
2. Description of the Prior Art
In U.S. Pat. No. 4,055,359, issued to McWethy, and assigned to Ford Motor Company of Deerborn, Mich., there is discloses a quick-connect tubular coupling known as the Springlock.RTM.. The Ford Motor Company has utilized these push-on fittings with garter-type coil springs on automotive air conditioning fluid lines and fuel lines for some time. These push-on fittings utilize two mated couplings which incorporate O-rings to seal the connection between the two couplings and which are subject to failure due to vibration and wear.
The end of the push-on fitting, described in the above-referenced United States patent, is flared and sized to fit into a cage which houses a garter-type coiled spring. The fitting is pushed onto a pipe and over the O-rings mounted on the end of the pipe until the flared end of the push-on fitting enters the cage and forces the coil spring over the flared end of the pipe and down to encircle the fitting. The coil spring then prevents the fitting from being pulled out of the cage. Fluid within the line under pressure is sealed within the line by the O-rings which are situated between the pipe and the push-on fitting. Push-on fittings of this type have been used to connect a flexible hose to the condenser, evaporator, accumulator and the compressor of the automotive air conditioning systems manufactured and sold by the Ford Motor Company, and also for connections to the gasoline tank and fuel injection system or carburetor of such vehicle's fuel system.
The fluid lines of automotive air conditioning systems conventionally operate with pressures of at least one hundred p.s.i. and at high ambient temperatures, line pressures of three hundred p.s.i. are not uncommon. These pressures put severe strain upon the seal between the push-on fitting and the pipe to which the fitting is coupled, which often results in a high incidence of O-ring failures causing leaks in the system. Additionally, the constant vibration and movement of the flexible hose during the running of the vehicle's engine and the vehicle itself over the ground will force the fitting to move back and forth transverse to its axis, causing wear and eventual rupture of the seal between the O-rings and the inner surface of the push-on fitting.
Recently, U.S. Pat. No. 4,728,130, issued to George S. Corzine, disclosed a locking assembly for utilization with such push-on fittings which holds the fitting in axial alignment to prevent the wear and leaking associated with misalignment and vibration. The locking assembly disclosed in the aforementioned United States patent includes an axially split internally threaded locking nut and an axially split externally threaded male fitting. The axially split internally threaded locking nut is coupled around the cage of the fitting and secured utilizing several set screws. Next, the axially split externally threaded male fitting is threaded into the internal threads of the other fitting, axially forcing the flared lip of the push-on fitting into the cage containing the coil spring. In this manner, the two portions of the push-on fittings are forced together axially and vibration and misalignment are substantially reduced.
U.S. Pat. No. 4,750,762, issued to the aforementioned George S. Corzine, discloses a second locking assembly for utilization with such push-on fittings which utilizes radial pressure to attempt to prevent wear and leakage of the fitting. The locking assembly disclosed in this patent utilizes an axially split coupling which includes a recess adapted to fit around the cage of a push-on fitting and which is secured around the fitting by utilizing two set screws such that radial pressure is exerted upon the fitting with the tightening of the set screws.
A problem has developed with both of the aforementioned devices in that the tolerances necessary to promote axial alignment are difficult to obtain in view of the variances found in the external dimensions of these Ford push-on fittings.
Thus, should the cage containing the coil spring be slightly undersized or oversized, it is difficult to maintain the two fitting assemblies in axial alignment utilizing a locking assembly which has been machined for close tolerances. Further, the complexity of a four-piece locking assembly has made application of such locking assemblies in tight quarters difficult to accomplish under ideal conditions and impossible in certain circumstances.
The cross-referenced U.S. patent application Ser. No. 07/197,667, by the inventor hereof, discloses a technique for accommodating variations which may exist in the external dimensions of the various components of such push-on fittings. In the aforementioned patent application, an axially split coupling is provided which includes a first circumferential recess adapted to generally receive the cage of a push-on fitting. A second separate circumferential recess is provided within the first circumferential recess to accommodate small variations in the external dimensions of the spring cage and a step flange is also provided to accommodate variations in the push-on fitting itself. However, this locking assembly, as well as all known locking assemblies, suffers from the inherent difficulties associated with manipulating two separate locking assembly halves as well as multiple locking screws within the restricted areas of an engine compartment.
Therefore, it should be apparent that a need exists for a simplified locking assembly which can be utilized to maintain the axial alignment of such push-on fittings which does not need to be manufactured to the extreme tolerances necessary in known prior art designs and which may be easily and simply attached to a push-on fitting.